Encoders Provide Path to High-Resolution Positioning

摘要

High-resolution interferential optical encoders are available with signal periods between 5 μm and below 130 nm and interpolation factors of 12-16 bit. They contain small grating interferometers with inherently low sensitivities to air turbulences.rnThe resulting spectral noise densities can reach 0.03...0.04 pm/(Hz)~(1/2). A proper mechanical design including a careful selection of materials reduces temporal and thermal drifts. Values of ～10 pm/hr have been demonstrated. High-frequency errors of encoders are dominated by interpolation errors. We demonstrated that amplitudes of 10 pm are achievable by using high-quality scales and compensating interpolation electronics.